This invention relates in general to fluorinated dimethyl ethers and specifically to methyl difluoromethyl ether as a starting material for the synthesis of fluorinated dimethyl ethers.
The synthesis of difluoromethyl ether, specifically bis(difluoromethyl)ether is described by the prior art as chlorination of dimethyl ether followed by the isolation and fluorination of bis(dichloromethyl)ether. Disadvantageously, the chlorination step gives a complex mixture of chlorinated dimethyl ethers some of which are unstable and thus prevent bis(dichloromethyl)ether from being harvested efficiently via distillation. In addition other intermediates such as chloromethyl methylether and bis(chloromethyl)ether are carcinogenic.
The aforementioned problems were overcome by the prior art by employing methyl difluoromethyl ether as a starting material. This process is described by the present applicant in allowed U.S. Ser. No. 875,553 which is hereby incorporated by reference.
The reaction between a sodium alkoxide and an alkyl halide to form an ether is well known and described in standard textbooks. See Organic Chemistry by Fieser and Fieser, page 141, incorporated herewith by reference. However, the literature is sparse regarding fluorinated ethers. U.S. Pat. No. 2,336,921 issued to Woodstown and Park discloses a reaction between a sodium alkoxide and an alkyl halide to produce a fluorinated diethyl ether only and not a fluorinated dimethyl ether, the subject of the present invention.
The synthesis of methyl difluoromethyl ether is described however by Hine and Porter in "Methylene derivatives as intermediates in polar reaction. VIII. Difluoromethylene in the Reaction of Chlorodifluoromethane with Sodium Methoxide" published in the Journal of the American Chemical Society 79, 5493-6 (1957), hereby incorporated by reference. Hine et al describe a reaction mechanism wherein the desired difluoromethyl-methyl-ether is synthesized in a batch reaction in a fixed ratio with the by-product trimethyl-orthoformate, while continuously refluxing the unreacted feed.
The drawback of the aforementioned difluoromethyl methyl ether synthesis is that large amounts of trimethylorthoformate are produced by the procedure in addition to the product itself breaking down to trimethylorthoformate. Both of which contribute to decreasing the difluoromethyl methyl ether production.
Accordingly it is a primary objective of the present invention to produce a high yield of difluoromethyl methyl ether.
A further objective of the present invention is to produce a high yield of difluoromethyl methyl ether, which in turn allows for a high yield of fluorinated dimethyl ethers.
A still further objective of the present invention is to produce a fluorinated dimethyl ether without producing unstable and/or carcinogenic intermediates.
Additional objectives will become known in the remaining application.